Strong earthquake swarm ongoing on Reykjanes ridge

At midnight on 1-August-2021 an earthquake swarm seems to have started deep on the Reykjanes ridge. The current distance seems to be around 220 km away from Reykjavík or 190 km from Grindavík town. At this distance the location from Icelandic Met Office are not accurate. At the writing of this article the earthquake swarm seems to be ongoing.

Earthquake activity deep on the Reykjanes ridge. Many green stars are on the map that goes south along the Reykjanes ridge
The earthquake activity as it is shown on Icelandic Met Office map. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake recorded at the writing of this article had a magnitude of Mw5,2 and the rest of the earthquakes have magnitude between Mw4,0 and Mw4,8. Overview of this earthquake activity can be found here on EMSC website. This links works as I publish this article. How long it is going to work I don’t know.

The current distance makes it impossible to know for sure what is going on at this location. The pattern of this earthquake activity suggests that this might be earthquake activity because of magma movement in the crust, but there is not any way to confirm this because of the location. Even if there is an eruption at this location it won’t make any difference to the surface of the ocean, since depth of the ocean at this location is more than 1 km. I don’t know the exact depth.

More earthquake activity in Katla volcano

Today (31-July-2021) at 12:53 UTC an earthquake with magnitude of Mw3,3 took place in Katla volcano. A swarm of smaller earthquakes continued after the largest earthquake, this earthquake activity seems to be ongoing at the writing of this article.

Earthquake activity in Katla volcano at 18:50 UTC this image shows three green stars, two of the stars are earthquakes from 29-July activity. New green star is from the earthquake today (31-July)
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

Summer earthquake activity in Katla volcano is common and that makes it less clear what is going on in Katla volcano at the writing of this article. There is now a chance of more earthquake activity in Katla volcano.

Earthquake activity in Katla volcano yesterday (29-July-2021)

Yesterday (29-July-2021) there was an earthquake activity in Katla volcano. Two strongest earthquakes had the magnitude of Mw3,2 at 19:20 and 19:22 UTC. Third largest earthquake at 19:28 UTC had a magnitude of Mw2,8.

Cluster of smaller earthquakes in blue and red colours inside Katla volcano caldera. Two green stars on the north-east side of the caldera show the largest earthquakes.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

It is unclear if this earthquake activity is just summer activity or part of a larger activity. At this time I am not expecting an eruption since the earthquake activity is currently too low for such event to about to take place. There are going to be thousands of earthquakes in Katla volcano before an large eruption. Until that happens. I do not worry about this activity.

More earthquake activity in Katla volcano

Today (28-July-2021) at 12:36 UTC an earthquake with magnitude of Mw3,1 took place in Katla volcano caldera. Few smaller earthquakes have followed the largest earthquake.

Green star in north-east part of the Katla volcano caldera where the magnitude 3,1 earthquake took place. One red dot in the same location shows a new earthquake that has happened there.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

This looks like a normal summer earthquake activity in Katla volcano. If that changes is impossible to know. There is no change in harmonic tremor on SIL stations around Katla volcano.

Strong earthquake activity in Bárðarbunga volcano

After a long while of not writing about Bárðarbunga volcano it is now time for new article.

On 27-July-2021 at 19:02 UTC an earthquake with magnitude of Mw3,9 took place in Bárðarbunga volcano. At 22:12 UTC an earthquake with magnitude of Mw4,5 took place in eastern part of Bárðarbunga volcano.  EMSC is reporting this earthquake as mb4,8. That information can be found here.

Earthquake activity in Bárðarbunga voclano shown by two green stars. One little to the west and the second one to the east in the rim of the main caldera.
Earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity in Bárðarbunga volcano is because there is now inflation going on in Bárðarbunga volcano. This inflation is going to continue until there is a new eruption. When that happens is impossible to know.

Earthquake activity in Ljósufjöll volcano

Today (26-July-2021) at 16:35 UTC an earthquake with magnitude of Mw3,0 took place in Ljósufjöll volcano. Earlier earthquake with magnitude of Mw2,2 also took place at 15:44 UTC.

Red dot on western Iceland shows the earthquake activity in Ljósufjöll volcano.
Earthquake activity in Ljósufjöll volcano. Copyright of this image belongs to Icelandic Met Office.

In this area there is also a fault zone that is between Langjökull and Snæfellsnes. That fault zone normally doesn’t have many earthquakes. With only activity happening every few decades and sometimes even less frequency. The area where the earthquake activity is inside the volcano named Ljósufjöll. Earthquake activity in this area started in May-2021. Currently its too early to know if this means anything, since this might just be earthquake activity and nothing more might happen, even if this earthquake activity is happening in a volcano.

More earthquake activity in Katla volcano

Since yesterday (24-July-2021) and until today (25-July-2021) there has been rather strong earthquake activity in Katla volcano. The earthquakes are not strong with largest earthquakes having a magnitude of Mw2,6. It is unclear what is going on.

Earthquake activity in Katla volcano caldera. A lot of yellow dots showing the locations of the earthquakes from south to north and then turn to east direction.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

One of the reasons this earthquake activity is happening is that cauldron might be emptying in the Mýrdalsfjökull glacier. That creates a drop in pressure that can start earthquake activity. I don’t know if that is what happened now. If that is what is going on it is going to take the melt water few hours to reach the rivers in Mýrdalssandur sand area. There has not been any change in harmonic tremor activity following this earthquake activity.

Earthquake activity in Katla volcano

Since 22-July-2021 there has been an earthquake activity in Katla volcano. This earthquake activity has been mostly located to the east of the caldera and largest earthquake so far detected had a magnitude of Mw3,0.

Earthquake activity to the east of Katla volcano caldera shown on the image by ring line. A second smaller cluster of earthquakes is the west and little bit inside the caldera of Katla.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

There has not been any change in harmonic tremor activity following this earthquake activity. That strongly suggest that this is normal summer earthquake activity for Katla volcano. Earthquake activity is also far too low for it to signal any eruption risk. That might change if earthquake activity changes and grows in size.

Deep earthquakes in Fagradalsfjall mountain

Today (21-July-2021) few deep earthquakes took place in Fagradalsfjall mountain that is part of Krýsuvík-Trölladyngja volcano system.

This earthquake activity was not big and the largest magnitude recorded was a magnitude of Mw0,8. Most depth that appeared had a depth of 13,4km.

Earthquake activity in Fagradalsfjalli mountain shown by a red dot, orange dots and few blue dots on Reykjanes peninsula.
The earthquake activity in Fagradalsfjall mountain on Reykjanes peninsula. Copyright of this image belongs to Icelandic Met Office.

It is difficult to know what this means. What is possibly happening is that more magma is pushing up in the magma feeding that now exist where the eruption has been happening. If that is happening, it can result in new craters or fissure opening up and start erupting. At the writing of this article this earthquake activity seems to be ongoing, but at slow rate and small earthquakes only so far.

Fog continues to block view to the crater and Fagradalsfjall mountain. But harmonic tremor data shows that the Fagradalsfjall mountain eruption is currently not erupting.

Update on the eruption in Fagradalsfjall on Saturday 17-July-2021

This is going to be shortest update to the eruption in Fagradalsfjall mountain that is part of Krýsuvík-Trölladyngja volcano system.

  • Since 9th July the eruption has been unstable. Between 10th July and 15th of July the eruption continued as before with pulsing activity.
  • On 15th of July at 05:00 the eruption stopped and it didn’t start again until around 10:00 on 16th of July.
  • At the writing of this article it seems that the eruption has stopped again based on the harmonic tremor.
  • The lava flows is down in Meradalir when the lava flow happens. At current rate it is going to take 1 to 4 weeks until Merdalir overflows with lava into next valley.
  • The east side of the crater has collapsed and that allows the lava flow direct flow down into Meradalir.

It is unclear why the eruption stops and starts again. One of my ideas is that the deep feeder system of the eruption is now empty and needs time to refill. The eruption stops when the feeder system is empty. The more empty it is the longer the eruption stops since it takes more time for the magma to fill up the magma chamber that seems to be there at 20km depth or more. How long this is going to go on I don’t know but I don’t think this can go on for many months or years. Current crater is at one point going to seal it self and the eruption is going to stop because of that.